Print this pageQuantification of Extension and Inversion Using Generalised Three Dimensional Volume Balance
WILLIAMS G. D,, T. S. SUDDIN, S. J. KANE, S. S. EGAN, D. HODGETTS, G. R. PEACE, and A. J. RICHARDS
The ability to manipulate volumetric data using computer workstations has enabled the generalisation of three dimensional balancing techniques in order to analyse areas with complex faulting histories. In regions that have undergone extensional faulting producing accommodation space filled by a syn-rift megasequence, followed by contractional inversion, it is possible to quantify the relative amount of each deformation mode using volume balance. Generalised three dimensional volume balance permits the analysis of reactivated faults with displacement gradients and it allows the modelling of dip-slip, oblique-slip and wrench faulting.
In this contribution we explain the concepts and methodology of three dimensional volume balance using complex kinematic models. In areas where fault surfaces are non planar, it is possible to obtain important information on fault movement direction by comparing the shapes of footwall and hanging wall cut offs on plan view -- the 'jigsaw fit' method. This parameter is vital in constraining the three dimensional faulting model. The volume of a syn-rift megasequence that fills fault generated accommodation space is used to calculate an extensional heave profile for the model and the volume of material above regional after inversion is used for the contractional heave profile. A combination of the two heave profiles yields a net profile that describes the present day fault configuration.
Case studies based on interpretations of seismic data cubes will be used to illustrate the three dimensional volume balance method and kinematic histories for regions which exhibit basin inversion will be presented.